Daytime sighting of planets is definitely possible but often difficult (as you have found), and Mars and Saturn are harder to detect against the bright sky background than Jupiter and Venus. I suspect that it doesn't take too much haze or other aerosols to reduce the contrast between planet and sky to the point of invisibility. This also makes it more difficult to see them for a given elongation “near” the Sun.
Depending upon how recently you attempted Mars, it may have been too close to the Sun to see against the brighter background sky near to the Sun. When did your attempt occur? I've seen Mars at 69 degrees elongation in daylight through an 89 mm aperture Questar, easily enough that I think it can be seen at somewhat closer elongations under good conditions. However, Mars was only 12 degrees elongation at the beginning of September, growing to 22 degrees elongation at the beginning of this month. By comparison, my closest sighting of Jupiter was 17 degrees elongation under somewhat mediocre sky clarity through my 90 mm apochromat, and it was rather difficult to see at that (and not visible at all in my Meade 90 mm ETX). Based on my experience, I'd bet that Mars may be impossible to detect at these small elongations, although I'd be delighted to be corrected by someone who has detected Mars this close to the Sun, perhaps at a site with excellent sky conditions.
Assuming you're able to point the telescope to the correct location (and your success in finding the others suggests that you can), be patient. Keep trying Mars, as its elongation will grow as we approach the next opposition, and you'll stumble on the day when sky conditions are excellent and it's far enough from the Sun to be detected.
Saturn may also be getting too close to be seen. I've seen it at about 90 degrees elongation, and it was not exactly a dazzling sight! It's a little over 70 degrees elongation right now. I tried once a couple of years ago when it was 75 degrees elongation and failed to see it. I don't know if it was inherently too close to be reliably detected, or maybe the sky conditions weren't optimal, but in any event I failed to see it.
One thing that is sometimes helpful,though not always, is the use of a single polarizing filter. I brought it up in a thread in the Solar System Observing forum. There's a link in that thread, near the end, to a previous thread about another observer's success with a single polarizing filter as well.
Hope this is helpful.